JP3713706B2 - Heat dissipation structure, package assembly, and heat dissipation sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat dissipation structure, a package assembly, and a heat dissipation sheet, and more particularly, to a heat dissipation structure, a package assembly, and a heat dissipation sheet that seal heat-generating electronic components and have excellent heat dissipation.
[0002]
BACKGROUND OF THE INVENTION
A substrate incorporating a package such as an IC or LSI is inspected in the same thermal environment as in actual operation. In the inspection, the same heat dissipation structure as in actual operation is used. Fins and heat sinks are known as heat dissipation structures. For the inspection, it is necessary to attach the package to be inspected to the heat dissipation structure before the inspection and to remove the package from the heat dissipation structure after the inspection. Such repeated attachment / detachment work, which is time-consuming, is a problem in terms of reducing the number of steps in the assembly process and the inspection process. In the middle of such work, using a high thermal conductivity material helps reduce man-hours. As such a material, a graphite sheet (hereinafter abbreviated as GS) is known. A band-shaped heat conductor is widely known in Japanese Utility Model Publication No. 58-135994, but a band-shaped heat conductor for heat dissipation in a sealed casing is not known.
[0003]
There is a need to simplify inspection work and further reduce costs for assembly and inspection. It is desired to reduce the number of man-hours using a high thermal conductivity material.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a heat dissipating structure, a package assembly, and a heat dissipating sheet that can simplify inspection work and further reduce the cost for assembly and inspection.
Another object of the present invention is to provide a heat radiating structure, a package assembly, and a heat radiating sheet that can increase the degree of heat discharge from a housing and the degree of freedom in designing a heat conduction path.
[0005]
[Means for Solving the Problems]
Means for solving the problem is expressed as follows. Technical matters appearing in the expression are appended with numbers, symbols, etc. in parentheses. The numbers, symbols, and the like are technical matters constituting at least one embodiment or a plurality of embodiments of the present invention, or a plurality of embodiments, in particular, the embodiments or examples. This corresponds to the reference numbers, reference symbols, etc. attached to the technical matters expressed in the drawings corresponding to. Such reference numbers and reference symbols clarify the correspondence and bridging between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence or bridging does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or examples.
[0006]
The heat dissipation structure for a package according to the present invention includes a base (2), a fin group (3) supported by the base (2), and a sheet (4) for transferring heat from a heating element (13) as an electronic component. It is composed of The sheet (4) has thermal conductivity and flexibility, and is thermally bonded to the fin group (3). The heat of the heating element is transmitted to the fin group promptly through the sheet (4). The heat generating element (13) is thermally bonded to the fin group (3) by a flexible sheet, and the heat dissipation test can be simply executed. In such a test, the relative position between the fin group (3) and the heating element can be freely changed, and the degree of freedom in the heat dissipation test is high. The use of GS with high thermal conductivity as a sheet has a higher ratio of the amount of heat transferred to the fin group (3) by heat conduction than the amount of heat released from the surface of the sheet in a natural environment. Reliability is improved.
[0007]
Filling the gap between the sheet (4) and the fin group (3) with a thermally conductive material can more effectively overcome the high thermal conductivity of the sheet. The formation of the recess into which the heating element (13) is fitted in the base (2) can simplify the procedure of the heat dissipation test.
[0008]
The package assembly according to the present invention includes a housing (16, 17), a substrate (12) supported by the housing (16, 17) in the housing (16, 17), and the housing (16, 17). Between the radiator (19 and 3 or 3 'in the state of FIG. 3) and the package (13) joined to the substrate (12). And a sheet (4) to be joined together. The sheet (4) has thermal conductivity and flexibility. The sheet (4) which is rich in flexibility can form a heat conduction path in the shortest possible distance in various component arrangement spaces arranged narrowly in the housing. The GS is effective as a sheet in an actual product without being limited to the heat dissipation test.
[0009]
The sheet (4) includes a heat dissipating part (5) thermally bonded to the radiator (3, 3 '), a heat absorbing part (6) thermally bonded to the package, a heat dissipating part (5) and a heat absorbing part ( 6) and a bent portion (7) which is bent. Thus, the heat conduction path can be freely formed in the housing. It is free in design that the heat dissipating part (5) and the bent part (6) have a common part.
[0010]
It is preferable that the sheet (4) comes out of the casing in contact with a watertight portion sandwiched between the casings. The radiator (3 ′) is a heat pump. In this case, the sheet (4) is thermally bonded to the heat pump (3 ′). The heat pump (3 ′) is joined to the housing (16 or 17) via the sheet (4). The heat pump (3 ′) is formed of a refrigerant container (27) and a refrigerant (28) sealed in the refrigerant container (27). The refrigerant (28) can be used in a mixed state of gas and liquid. In the refrigerant container (27) provided with the fin structure, the vaporized refrigerant gas quickly reaches the inner surface of the fin to increase the heat radiation efficiency. In this case, the heat pump has a function of a heat pipe.
[0011]
The addition of the thermal coupling body (2, 3) is preferable in that a heat dissipation test can be performed in a state close to an actual product. The housing (16) is formed with a group of fins projecting outward of the housing (16), and the fin elements (19) of the fin group each have a convex concave group that is convex outward as an inner surface. The formed thermal coupling body (2, 3) has a projection group (3) that is convex outward and is thermally bonded to the inner surface of the convex concave group. One end of the sheet (4) is thermally coupled to the thermal coupling body (2, 3), and the other end of the sheet (4) is thermally coupled to the package (13) coupled to the substrate (12). Is bound to. In this case, the projection group (3) is fitted into the convex concave group and is detachable, thereby simplifying the test procedure. Such a thermal coupling body (2, 3) can perform a heat dissipation test of an actual product with high reliability.
[0012]
The heat-dissipating sheet according to the present invention has the following environmental conditions: it passes through a sealed casing, is thermally bonded to a heat-generating package supported by an electronic substrate in the casing, and outside the casing. It is used under the condition of being thermally bonded to a heat radiating body that is bonded to the casing, and has high thermal conductivity and rich flexibility. The physical properties of GS are effectively used as means for heat dissipation in the housing.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Corresponding to the figure, in the embodiment of the heat dissipation structure according to the present invention, the heat dissipation structure is provided together with the flexible sheet. The heat dissipation structure 1 is formed of a base 2 and a fin group 3 as shown in FIG. The fin group 3 is formed by a plurality of fin elements 3a, 3b, 3c. The fin elements 3a, 3b, 3c are separated from each other and joined to the upper surface of the base 2. The fin elements 3a, 3b, 3c are wider on the side closer to the base 2 and wider on the side farther from the base 2, and each of the fin elements 3a, 3b, 3c is tapered. Thus, both side surfaces are formed as tapered surfaces. The width directions of the fin elements 3a, 3b, and 3c coincide with the direction in which the fin elements 3a, 3b, and 3c are arranged.
[0014]
The flexible sheet 4 includes a heat radiating side portion 5 that covers the fin group 3, a heat absorbing side portion 6 that is thermally bonded to the heating element, and a bent portion 7 that extends continuously from the heat radiating side portion 5 to the heat absorbing side portion 6. Formed from. The heat radiation side portion 5 extends with a proper length in the direction in which the fin elements 3a, 3b, 3c are arranged. The bent portion 7 extends in a direction substantially orthogonal to the heat absorption side portion 6.
[0015]
The back surface of the heat radiating side portion 5 is uneven along the tapered shape forming surfaces (the already described tapered surfaces) of the fin elements 3a, 3b, 3c, or deeply bent in a wave shape so as to be in close contact with the tapered shape forming surface The surface is formed. An engagement tool 8 is used to bring the heat radiation side portion 5 into close contact with the fin elements 3a, 3b, 3c. As shown in FIG. 1A, the engaging tool 8 has engaging holes 9 corresponding to the positions of the fin elements 3a, 3b, 3c. Further, the engaging tool 8 is integrally formed with hooks 11 that are detachably engaged with the four peripheral positions corresponding to the four peripheral positions of the base 2.
[0016]
The hole width of the engagement hole 9 is substantially equal to the above-described width in the vicinity of the respective base portions of the fin elements 3a, 3b, 3c. The engagement tool 8 is pushed down toward the heat dissipation structure 1 with an appropriate pressure. If the fin elements 3 a, 3 b, 3 c are inserted into the engagement holes 9 of the engagement tool 8, the wavy uneven portion of the heat radiating side portion 5 It is pinched | interposed with a surrounding surface, and it clamp | tightens by appropriate fastening force with the fin elements 3a, 3b, 3c and the engaging tool 8. FIG. Due to the tightening force and the engagement force between the hook 11 and the bottom surface of the base 2, the heat radiation side portion 5 is stably coupled to the fin group 3, and the heat radiation structure 1 is attached to the flexible sheet 4. Bonds stably.
[0017]
Filling the minute gap between the back surface of the heat radiation side portion 5 and the surface of the fin group 3 with the high thermal conductivity grease exchanges heat between the fin group 3 and the heat radiation side portion 5 with high efficiency. It is particularly important in that it can. The flexible sheet 4 is made of a material having high thermal conductivity, and GS described above is particularly suitable. The thermal conductivity of GS is three times that of aluminum, twice that of copper, and excellent in flexibility. When the engagement tool 8 is not used, the fin group 3 and the heat radiation side portion 5 can be joined with a thermosetting adhesive. The flexible sheet 4 is a composite sheet in which the central layer has the above-described physical properties related to thermal conductivity, and both surfaces of the central layer are coated with a heat insulating material, and the flexibility is not lost as a whole. preferable.
[0018]
As shown in FIG. 2, the base 2 is attached to the package attachment substrate 12. The package 13 is mounted on the package mounting substrate 12. A recess 14 (see FIG. 1) is formed on the lower surface side of the base 2. An engagement jig 15 is used in which a concave surface that approximately coincides with the convex surface formed by both side surfaces and the upper surface of the package 13 is formed. When the engagement jig 15 is fitted into the package 13, the heat radiation side portion 6 of the flexible sheet 4 is sandwiched between the convex surface of the package 13 and the lower surface of the engagement jig 15. By such sandwiching, the flexible sheet 4 is mechanically and thermally coupled to the package 13. The base 2 is detachably coupled to the package 13. Although it is meaningful to perform the heat dissipation test in the state shown in FIG. 1, as will be described later, it is also effectively used for testing actual products.
[0019]
FIG. 3 shows an assembled state in which the package mounting substrate 12 is assembled together with the heat dissipation structure 1 and the flexible sheet 4 in the housing of the actual product. The casing is composed of an upper casing 16 and a lower casing 17. The upper housing 16 and the lower housing 17 are coupled to each other by bolts 18 at their flanges. The ceiling portion of the upper housing 16 is formed in a fin group. As shown in FIG. 4, a tapered concave surface 21 is formed on the lower surface of the plurality of fin elements 19 in a part of the fin group. A fitting surface 22 into which the upper surface of the base 2 and the peripheral surface of the base 2 enter is formed on the rear surface side of the upper housing 16 continuously from the tapered concave surface 21.
[0020]
The heat dissipation structure 1 is fitted into the package mounting substrate 12 as shown in FIG. The inspection is performed in the attached state shown in FIG. The heat generated when the package 13 generates heat is conducted to the flexible sheet 4 and transmitted to the fin group 3 at a position separated from the package 13 via the flexible sheet 4. Part of the heat of the package 13 is conducted to the fin group 3 through the engagement jig 15 and the base 2. The heat dissipation of the heat dissipation structure that dissipates the heat of the package 13 is close to the heat dissipation during actual operation.
[0021]
A highly heat-conductive material is applied to the sharp concave surface of the fin element 19 or the convex surface of the fin group 3, and then the fin group 3 integral with the base 2 is inserted into the sharp concave surface of the fin element 19. As the high thermal conductivity material, magnesium powder is preferably used by blending with a rubber-based resin. The fin group 3 is mechanically elastically pressure-bonded to the fin element 19 through such a rubber-based resin, and is thermally coupled. The flexible sheet 4 bonded to the base 2 is inserted into the fin element 19 together with the base 2, and the other substrate 23 is assembled to the upper housing 16 via the column 24 as shown in FIG. 3. Another package 25 is already attached to the other substrate 23. The other package 25 is thermally bonded to the ceiling surface of the upper housing 16. Next, the free end portion side of the sheet 4 is attached to the package attachment substrate 12 that has finished the temporary operation, and the package attachment substrate 12 is attached to the column 24. Finally, the lower casing 17 is coupled to the upper casing 16 by screwing.
[0022]
After such overall assembly, an actual operation inspection is performed. The heat of the package 13 is transmitted through the flexible sheet 4 to the base 2 and the fin group 3 of the base 2. The heat of the fin group 3 is transferred to the fin element 19 and exchanges heat with the atmosphere on the surface of the fin element 19. The heat diffused throughout the casing 16 is dissipated from the other fin group 26 formed in the upper casing 16.
[0023]
The flexible sheet 4 is thin but wide, and is thermally bonded to the fin element 19 over a wide area, so that a large amount of heat of the package 13 can be transferred to the fin element 19. Since the flexible sheet 4 is rich in flexibility and can be freely arranged in the housing, it is unlikely to obstruct assembly. The assembly structure of the package 13, the package mounting board 12 and the fin group 3 shown in FIG. 2 is incorporated in the housing as shown in FIG. 3 as it is, so that the package 13 and the fin group 3 are temporarily connected. There is no need to attach and detach each inspection, and the fin group 3 is used both for inspection and for the final product, reducing the number of inspection and assembly steps. The inspection fin fits into the final fin, and the final product is compact. The flexible sheet 4 is flexible and can transmit the heat of the package 13 to a freely set site without impeding the freedom of assembly of the package mounting substrate 12.
[0024]
FIG. 5 shows another embodiment of a package assembly according to the present invention. The first substrate 12 on which the first package 13 is mounted is attached to the casing (upper casing 16), and the second substrate 23 on which the second package 25 is mounted is mounted on the casing (lower casing 17). The attachment point is the same as that of the embodiment described above. The fact that the heat absorption side portion 6 of the flexible sheet 4 is thermally coupled to the package 13 and the heat radiation side portion 5 of the flexible sheet 4 is thermally coupled to the heat radiator is described above. The form is the same. The radiator of the present embodiment uses a cooler 3 ′ instead of the fin group 3.
[0025]
The cooler 3 ′ is thermally and widely joined to the outer surface of the cooler 3 ′ via the heat radiation side portion 5. The cooler 3 ′ includes a refrigerant container 27. A refrigerant 28 is sealed in the refrigerant container 27. A gas / liquid mixed material is enclosed as the refrigerant 28. The gas / liquid mixed material takes the heat of vaporization from the container wall portion joined to the heat radiation side portion 5 and evaporates, and transfers the heat to the container wall portion having the outer surface of the refrigerant container 27. The refrigerant container 27 forms a kind of heat pipe or heat pump. If the fin is formed in the refrigerant container and the inner surface of the fin is formed in a wavy surface, the vaporized refrigerant gas is liquefied on the inner surface of the fin, and the function of the heat pipe or heat pump is enhanced.
[0026]
The bent portion 7 of the flexible sheet 4 protrudes outside the housing. The length of the flexible sheet 4 in the housing is relatively short. A packing ring 29 is interposed on the joint surface between the upper housing 16 and the lower housing 17. As shown in FIG. 6, a part of the flexible sheet 4 is sandwiched between the packing ring 29 and the housing, and the inside of the housing is kept watertight. Although the inside of the housing is sealed, the heat of the package, which is an electronic component, is quickly discharged out of the housing due to the high thermal conductivity of the sheet 4.
[0027]
FIG. 7 shows yet another form of implementation of the package assembly according to the present invention. The bent portion 7 of the flexible sheet 4 is passed through a slit 31 formed in the upper housing 16, and the heat radiating side portion 5 of the flexible sheet 4 is in close contact between the cooler 3 ′ and the upper housing 16. Is interposed. The flexible sheet 4 reaches the outer surface of the upper housing 16 from the package 13 in the shortest course. A space between the hole surface of the slit 31 and the bent portion 7 is filled and sealed with an appropriate filling and sealing material. A packing ring 29 is interposed between the upper housing 16 and the lower housing 17 in a watertight manner. The heat generated in the package 13 is transmitted to the outside of the casing through the flexible sheet 4 at the shortest distance (minimum heat dissipation area in the casing), and the temperature rise of the sealed space in the casing is effectively suppressed to a low level. It is preferable that the other fin group 32 is provided in the lower housing 17 in terms of improving heat dissipation. In this embodiment, the heat dissipation performance is improved, and the degree of freedom in the layout of the substrate and the package in the housing is increased.
[0028]
FIG. 8 shows still another embodiment of the package assembly according to the present invention. In the present embodiment, expansion fins 33 are added. The expansion fins 33 are joined to the upper housing 16 or the lower housing 17. The flexible sheet 4 is sandwiched between the packing rings 29 and extends outside the housing, and is thermally bonded to the expansion fins 33 thermally. In the present embodiment, the heat radiation side portion 5 coincides with the bent portion 7.
[0029]
【The invention's effect】
With the heat dissipation structure, the package assembly, and the heat dissipation sheet according to the present invention, the heat of the package, which is an electronic component in the casing, is quickly discharged out of the casing, and the degree of freedom in designing the heat conduction path is high.
[Brief description of the drawings]
FIGS. 1A and 1B are oblique axis projection views respectively showing two aspects of an embodiment of a heat dissipation structure according to the present invention.
FIG. 2 is an oblique projection view showing another embodiment.
FIG. 3 is a cross-sectional view showing another embodiment of the heat dissipation structure according to the present invention.
FIG. 4 is a cross-sectional view showing a part of FIG. 3;
FIG. 5 is a cross-sectional view showing still another embodiment of the package assembly according to the present invention.
6 is a cross-sectional view taken along the line VI-VI in FIG. 5;
FIG. 7 is a cross-sectional view showing still another embodiment of the package assembly according to the present invention.
FIG. 8 is a cross-sectional view showing still another embodiment of the package assembly according to the present invention.
[Explanation of symbols]
2 ... Base 2, 3 ... Thermal coupling body 3 ... Fin group 3 '... Heat pump 3, 3' ... Radiator 4 ... Sheet 5 ... Heat radiation part 6 ... Heat absorption part 7 ... Bent part 12 ... Substrate 13 ... Heating element (package)
16, 17 ... casing 19 ... radiator 27 ... refrigerant container 28 ... refrigerant

Claims (5)

  Base and
A group of fins supported by the base;
A heat-absorbing part to be joined to a heating element that is an electronic component; a bent part that can be bent; and a heat-dissipating part that is disposed so as to cover the fin group and dissipates heat from the heating element to the fin group; A sheet having heat conductivity and flexibility,
Equipped with
Heat dissipation structure.   A heat dissipating structure according to claim 1,
A gap between the sheet and the fin group is filled with a heat conductive material.
Heat dissipation structure.   A heat dissipating structure according to claim 1,
The base has a recess into which the heating element is fitted.
Heat dissipation structure.   A heat dissipating structure according to claim 1,
Furthermore,
An engagement hole corresponding to the position of the fin group, and a hook detachably engaged with the base corresponding to the periphery of the base, with the sheet disposed so as to cover the fin group interposed therebetween Engagement tool detachably attached to the base
Equipped with
Heat dissipation structure.   The heat dissipation structure according to any one of claims 1 to 4,
The heat dissipation portion and the bent portion have a common portion
Heat dissipation structure.

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